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데이터센터의 외기도입 냉방시스템 적용에 따른 경제성 평가
박성현(Seonghyun Park),서장후(Janghoo Seo) 대한설비공학회 2014 설비공학 논문집 Vol.26 No.4
Many studies are being conducted with the aim of reducing the energy consumption in data centers, which are one of the highest consumers of energy. The use of an air-side economizer system that uses external air during intermediate and winter seasons is being considered for reducing the energy consumption of air conditioners. In this study, using the energy simulation, we evaluated the energy performance of a central chilled water cooling system and air-side economizer system in domestic data centers. Further, the cost-effectiveness of the air-side economizer was analyzed through Life-Cycle Cost Analysis. The results showed that with the use of air-side economizer systems, the energy costs increased as the applied filter grade increased; however, unlike existing central chilled water systems, it would break even within 2 years.
실리콘 오일 점도에 따른 ABS-like 레진의 트라이볼로지 특성
박성현(Seonghyun Park),손준규(Jungyu Son),우성웅(Seongwoong Woo),류의진(Euijin Ryu),이현섭(Hyunseop Lee) 한국트라이볼로지학회 2020 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.36 No.6
Recently, additive manufacturing (AM) technology has been applied to various industries such as automotive, aviation, medical, and electronics. Most prior studies are limited to the mechanical properties of printed materials, and few studies are being conducted on their tribological characteristics. However, the friction and wear characteristics of the material should be studied in order to utilize the components manufactured using AM technology as mechanical parts. In this study, the friction and wear characteristics of acrylonitrile-butadiene-styrene (ABS)-like resin printed with stereo lithography apparatus (SLA) 3D printing are evaluated according to the viscosity of silicon oil lubricant using a ball-on-disk experiment. Lubricants with a viscosity of 500, 1000, and 2000 cSt are prepared for the experiment. If silicon oil lubricants are used during the ball-on-disk test, the coefficient of friction (COF) and wear rates are significantly reduced, and the higher the viscosity of the lubricant, the lower will be the COF and wear rates. It is also verified that the temperature of the specimen owing to friction also decreases according to the viscosity of the lubricant. This is because of the silicon oil film thickness, and the higher the viscosity of the lubricant, the thicker will be the oil film. More studies on the tribological characteristics of 3D printing materials and suitable lubricants will be required to use 3D printed parts as mechanical elements.
머신러닝을 이용한 안드로이드 멀웨어 탐지에서 API 호출의 효과 분석
박성현(Seonghyun Park),강문영(Munyeong Kang),박지현(Jihyeon Park),조성제(Seong-je Cho),한상철(Sangchul Han) 한국정보과학회 2021 정보과학회논문지 Vol.48 No.3
본 논문은 API 호출 정보의 표현 방식과 전처리 방식이 안드로이드 악성 앱 탐지 시스템의 정확도에 미치는 영향을 평가한다. 민감한 데이터를 접근 또는 제어하는 API 호출 정보를 앱에서 추출하여 머신러닝의 특징정보로 사용할 때, 추출한 API 정보를 어떤 방식으로 활용하는 것이 좋은가를 분석한다. 본 논문에서는, API 호출 이름만을 고려, API 호출 빈도 고려, API 호출 인자 및 리턴타입 포함 등의 방식으로 API 호출 정보를 표현하고 전처리하여 머신러닝 알고리즘을 적용한다. 실험 결과, 특징정보에 API 호출 인자 및 리턴타입을 포함하고 호출 빈도를 표현한 경우에 미세하게 높은 정확도를 보였으며, 특징정보 크기 측면에서는 호출 API의 클래스 이름과 메소드 이름, 존재 여부만을 표현한 경우가 가장 효율적이었다. This paper evaluates the effect of preprocessing and representing API call information on the accuracy of the system to detect malicious Android apps. We extract API calls that access or control sensitive data from target apps, and use the calls in machine learning algorithms to detect malicious apps. We then determine which expression of the API calls is most effective in classifying the apps as malicious or benign. Four ways of representing each API call are considered: class/method name with and without arguments/return type, and its presence (whether an API is called or not) and its frequency if called. The detection system has performed slightly better when the arguments/return type and the frequency of each API call were considered together. Its feature size was most efficient when considering the class/method name and the presence of each API call.
전해 이온화와 자외선광을 이용한 사파이어 화학기계적 연마의 재료제거 효율 향상에 관한 기초 연구
박성현(Seonghyun Park),이현섭(Hyunseop Lee) 한국트라이볼로지학회 2021 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.37 No.6
Chemical mechanical polishing (CMP) is a key technology used for the global planarization of thin films in semiconductor production and smoothing the surface of substrate materials. CMP is a type of hybrid process using a material removal mechanism that forms a chemically reacted layer on the surface of a material owing to chemical elements included in a slurry and mechanically removes the chemically reacted layer using abrasive particles. Sapphire is known as a material that requires considerable time to remove materials through CMP owing to its high hardness and chemical stability. This study introduces a technology using electrolytic ionization and ultraviolet (UV) light in sapphire CMP and compares it with the existing CMP method from the perspective of the material removal rate (MRR). The technology proposed in the study experimentally confirms that the MRR of sapphire CMP can be increased by approximately 29.9, which is judged as a result of the generation of hydroxyl radicals (·OH) in the slurry. In the future, studies from various perspectives, such as the material removal mechanism and surface chemical reaction analysis of CMP technology using electrolytic ionization and UV, are required, and a tribological approach is also required to understand the mechanical removal of chemically reacted layers.
데이터센터에 적용된 외기도입 냉방시스템에서 필터유형별 에너지 소비량 변화
박성현(Seonghyun Park),서장후(Janghoo Seo),정용호(Yong-Ho Jung),장현재(Hyun-Jae Chang),황석호(Seok-Ho Hwang) 대한설비공학회 2013 설비공학 논문집 Vol.25 No.7
Recently, many studies related to reducing the energy consumption in data centers have been conducted. These studies have mainly focused on the air intake and exhaust system of a computer room air handling unit (CRAH) in the server room, diffuser type, suppression and discharge of the heat generated from the server, and the air-side economizer system. In this study, the energy consumption of the conventional central chilled water cooling system is compared with the energy consumption of the air-side economizer system. We also examined how changes of differential pressure by each filter have influenced energy consumption, using the power usage effectiveness (PUE). Results show that the PUE was improved, and energy consumption decreased, by applying the air-side economizer system.